A light-emitting element is normally mounted on a substrate and moreover packaged by sealing the light-emitting element with a transparent resin in order to protect it from the external environment such as external forces and humidity and the like. In addition, a convex part of a lens is sometimes formed on the upper portion of the sealing resin in order to perform control such as converging and diffusing of light that is emitted from the light-emitting element. To form such a lens shape, for example, the resin is raised by surface tension prior to curing and subjected to heat curing or ultraviolet curing while maintaining that shape, whereby it is possible to finish the upper portion of the sealing resin in a lens shape (for example, refer to Patent Document 1).
In the method of manufacturing this kind of lens shape, the amount of raising of the resin to be raised is significantly affected by the wettability of the substrate and resin. For example, due to variations in the surface condition of the substrate and the like, when the coating amount of the sealing resin is excessive or the wettability of the substrate surface is high, the resin may flow out on the upper surface of the substrate prior to curing. Removing his resin takes time and effort, and sometimes the resin that has flowed out may cover electrodes that are provided on the substrate side face. In the case of attempting to anchor the substrate by soldering, the resin that has become attached to the electrodes may act as an electrical insulating film, leading to the problem of poor electrical conduction.
In recent years, the application of LEDs has advanced to lighting uses and traffic signals, and further improvements in luminescence intensity are demanded. By increasing the amount of electrical current that is impressed, it is possible to increase the luminescence intensity of an LED. However, in this case, it is necessary for the light-emitting element to efficiently dissipate the heat because the light-emitting element accompanies the heat generation simultaneously. In the case of the heat dissipation being insufficient, the light-emitting element reaches a high temperature when lit. As a result, the light-emitting efficiency falls and so the target luminescence intensity is no longer obtained. Also, when used over a long period, the reliability of the LED falls, and the possibility of malfunction such as non-lighting increases.
In addition, in order to efficiently emit the light forward that is radiated from the light-emitting element, it is preferable to provide a reflective concave portion as shown in FIG. 4. The package structure of the light-emitting element shown in FIG. 4 uses a package 1 that has a reflective concave portion 2 with a mortar-like shape, electrodes 3 of which a portion thereof extends into the reflective concave portion 2, and a light-emitting element 4 such as an LED mounted on one electrode 3 in the reflective concave portion 2 of this package 1. The light-emitting element 4 and the other electrode 3 are electrically connected by a gold wire 5, and a sealing resin 6 is filled in the reflective concave portion 2 so that the upper portion rises upward, and then cured so as to form a lens shape. In the light source of this package structure, the light-emitting element 4 is lit up by electrical conduction between the electrodes 3, and a portion of the light that is generated from the light-emitting element 4 is directly emitted while the other portion is emitted by being reflected by the reflective concave portion 4. Therefore, it is possible to efficiently emit the light that is generated from the light-emitting element 4 to the front of the package.
Patent Document 1: Japanese Unexamined Patent Application, First Publication No. H09-153646